1. Field of the Invention
The present invention generally relates to the sortation of articles into a plurality of groups, each in a desired sequence and, more particularly, to sorting of articles, such as postal flats, in accordance with intermediate or final destinations such as delivery points along each of a plurality of delivery routes for mail or other delivery services.
2. Description of the Prior Art
The pace of commerce and volume of written communications has increased annually for many years to the point that tens, if not hundreds, of millions of articles are sent from many locations to any of millions of delivery points daily. The articles will generally be in a random order when deposited with a carrier such as the United States Postal Service and then will be aggregated with articles from many other senders prior to being sorted for transportation to a regional facility in the general vicinity of the addressee, thence to a local office and finally to a carrier for delivery to a specified final delivery point.
The volume of articles handled by a given carrier has become quite large and the number of delivery points along each delivery route (as well as the number of routes provided) has increased with increases in the general population and improvements in level of delivery services. Accordingly, it is necessary that all phases of the sortation and processing of articles for delivery be carried out with increased accuracy and speed. For example, it is not possible to read addresses and manually sort all articles which may be deposited with a delivery service. For this reason, central facilities have employed a high degree of automation using bar code readers and/or character recognition to perform basic sorting of articles to be transported to defined geographic regions or to local offices within those regions. Further, a plurality of those geographical regions may be served by a single vehicle, such as an aircraft, along a route which is repeated daily.
The problem of handling large volumes of articles is more aggravated and less tractable at the level of carrier delivery routes. Carriers must traverse their assigned routes in the shortest possible time and the time available is not sufficient for verifying the address provided for each article in accordance with each of a large plurality of delivery points. By the same token, if a delivery of one or more articles is not made as the carrier visits each delivery point, no time is available to retrace a potentially large portion of a delivery route in order to make the delivery, and delivery must be postponed to the following day. If a delivery is erroneously made at a given delivery point, it may be several days before the recipient redeposits the article with the carrier and an additional period of time required for another, hopefully correct, delivery to be made. Further, the orientation of the articles in relation to the addresses placed thereon is an additional source of inconvenience to the carrier and errors in delivery.
Accordingly, it is seen that sortation of articles for delivery must be automated at virtually all levels of the delivery process. However, at the present time, only a single level of sorting is generally available in currently used processes and is only practical at major collection centers and distribution points. A multiple pass process is, however, disclosed in Keough, U.S. Pat. No. 5,009,321, but requires a first pass for addresses to be read by an optical character reader and labelling with a bar code label which is thereafter used for a multiple-pass sorting process; the first sorting pass separating the articles into bins and multiple further passes to reach a delivery sequence order. The bar-code labelling process and additional sorting steps required involves additional processing time and sorting machine overhead as well as additional operator involvement and defacement of the individual articles to reach the result of delivery order sequence.
Moreover, no automated facility is presently available which has the potential for improving accuracy and speed of delivery at the local carrier route level. Many delivery errors and many instances of inefficiency are occasioned by errors in the order in which articles or groups of articles are placed which requires additional perusal of the intended delivery address numerous times in the course of a correct delivery or the failure of a carrier to find all articles to be delivered to a given address at the time the carrier reaches that address.
Further, no known system presents the articles in a given orientation using standard (e.g. USPS) flats tubs with regard to an address affixed thereto as well as in order of delivery point at any level of the delivery process. Accordingly, the likelihood of sorting and/or delivery errors as well as handling time is increased.
In regard to the United States Postal Service (USPS) at the present time, a further problem is presented which may be shared by other delivery services in the near future. Specifically, the USPS has standardized the dimensions, weight and other characteristics of tubs made of wire-reinforced corrugated sheet plastic used to manually transport mail. These tubs have been manufactured in great numbers and are in widespread use throughout the United States. Standardization of such tubs, of course results in many efficiencies for packing and transporting mail items as well as providing convenience, such as effectively limiting the weight of articles which may be placed therein by imposing a limit on the volume thereof, to personnel who must manually carry them. However, for purposes of mechanically sorting mail and placing articles in delivery order, these tubs present several practical problems.
First, the tubs have a length and width that exceed the dimensions of the largest"flats" (e.g. large envelopes which exceed normal"letter" dimensions, generally between 6.times.9 inches and 12.times.18 inches) so that a flat cannot become wedged between all four sides of the tub from which it would be difficult to extract but can become displaced between a stack of flats and a side of the tub which both violates ordering of the flats and presents difficulty in retrieval from the tub. The permitted variability of the dimensions of flats relative to the dimensions of a USPS tub also allows smaller flats to be accommodated side-by-side which is, by definition, out of order.
Second, flats will not only have different dimensions but may be of greatly varying thicknesses and weights. Therefore, each flat will have different aerodynamic characteristics when it is placed in the tub. That is, when a flat is released from a mechanical sorting machine at some finite horizontal velocity, it will "fly" or tumble unpredictably and orientation of the flat in the tub cannot be assured. The dimensions of the tubs and the random and increasing height of a stack of flats which may be placed in the tub (as well as their possible fragility) do not permit the insertion of any mechanism into the tubs which would be effective to restrain such random tumbling effects.
Previous efforts to maintain orientation of flats has been approached by the use of specially designed tubs which were specific to a particular mechanical sorting apparatus. However, such tubs were not optimally suited to transportation of articles by the operator of the mechanical sorting machine for the multiple pass sorting processes which have been required. (U.S. Pat. No. 5,009,321 is exemplary of such sorting processes in which a first pass uses optical character recognition to apply a bar code to the article which is used in subsequent sorting passes but generally undesirable since it alters the appearance of the article and is considered defacement of the article. A second pass sorts by region or route and multiple further passes are required to place the flats in delivery order. Each pass with its corresponding insertions of flats into tubs while possibly providing for rotation of flats into a desired orientation, can result in flats being later reoriented into different, undesired, orientations.) Further, once sorting and ordering of flats has been accomplished, the flats must then be manually transferred to the USPS standard tubs for transportation and delivery. This further transfer can also be a source of errors in ordering and/or orientation since the flats can shift horizontally against each other in an uncontrollable fashion during such transfer.
In summary, while it is evident that much economy and improvement in delivery service could be obtained by accurate sorting, ordering and orientation of articles to be delivered in accordance with established and generally optimized delivery routes, and while substantial efforts have been made toward providing such sortation, efficient sorting techniques have not yet been developed that avoid the marking of articles and which minimize the number of passes necessary to achieve the desired sortation. Further, no mechanical sorting apparatus has been developed which can accommodate use of USPS standard tubs to directly receive sorted articles without compromising the ordering and/or facing (e.g. face-up and desired address orientation) of articles.